Emulsions are two-phase systems consisting of two incompletely miscible liquids, one being dispersed as finite globules in the other. The dispersed, discontinuous, or internal phase is the liquid that is broken up into globules. The surrounding liquid is known as the continuous or external phase.
Aqueous based lubricants and functional fluids have been greatly in demand because of their low cost, but also because of their ease of disposal, reduced dependence on supply of petroleum-derived base fluid, and their fire resistance.
Alkali metal borates are well known in the oil-based lubricant and grease art for their extreme pressure properties. See for example, U.S. Pat. Nos. 4,100,081; 3,997,454; and 3,313,727. Dispersions of alkali metal borates, however, have not been previously used in oil-in-water emulsion fluids.